"At least I had chicken." - Old Klingon Proverb
Leeroy Jenkins is a loan-word/meme that originated on /v/, but which has been readily absorbed into the /tg/ lexicon. It refers to an individual who constantly ruins battle plans by charging headfirst into battle, not bothering with their companion's approval and no matter the odds, usually because they're too stupid or impatient to wait or to try and keep to any sort of strategy.
The Leeroy Jenkins meme began with a World of Warcraft fan-made video that was intended to mock overly complicated plans and "overthinkers". Said video was a re-enactment of a famous run on one of the Blackrock dungeons. One of the rooms in the dungeons is filled with dragon eggs; if you walk too close to them, the eggs hatch, and the baby dragons will cause other eggs to hatch if you aren't careful, so the fight is about moving very carefully around and dealing with small groups of opponents at a time so you don't end up drowning in dozens of baby dragons. Well, on one fateful day a group came through that didn't really want to fight dragons, so the leader painstakingly explained a procedure to sneak around the edges and avoid the fight. One group member however, really wanted to kill some dragons. So, promptly ignoring the leader's strategy, he took off across the room with a great cry of "LEEEEEEEEEEROOOOOOY" into the team chat, causing every single dragon egg to hatch. You can guess the results of that.
Despite the given context of mocking overthinkers, the video's protagonist has been adopted as the villain on /v/ and /tg/ simply because that particular flavor of blindly aggressive player is well known in both circles as one of the most common and annoying branches of That Guy's family tree. A particularly annoying variant will actually pick fights needlessly just for the sake of having someone to fight, usually because the player finds planning, talking, etc to be "boring". For instance, the original Leeroy supposedly went for some KFC leftovers while his team leader was explaining things (hence the otherwise nonsensical punch line of "At least I had chicken!"), not bothering to listen to a single word of the strategy. Leeroys are, ironically, rarely munchkins - or at least not very good ones - since your typical munchkin wants to "win" and understands that blindly attacking every foe in sight isn't likely to succeed.
Leeroys on the Tabletop
The 1e Dungeons & Dragons Cavalier-Paladin earned its particular amount of scorn because it took the Paladin's "crunch-mandated fluff" of Lawful Stupidity and not only did it have to do the same thing, it also enforced this very behavior in the exact same way. Specifically, as a result of the code and the desire for battle, cavaliers cannot be controlled in battle situations. They will charge any enemy in sight, with this order of preference:
- Powerful monsters (dragons, demons, giants) serving enemy leaders.
- Enemy leaders.
- Opponent cavaliers of great renown, and enemy flags and standards.
- Opponent cavalry of noble or elite status.
- Other opponent cavalry.
- Opponent elite footmen.
- Opponent camp and headquarters.
- Opponent melee troops.
- Levies or peasants.
So, you have a class that is not only expected to act like this, but which gets game penalties if it doesn't. Not a lot of people approved, obviously.